The only goal of the first rotation is to increase the velocity of the pocket to within just a hair of the actual escape velocity. Probably the least known thing about slinging is the number of times you need to do this. The surprising answer is... ONCE! three times at the very most. First time slingers love to helicopter the pocket around their head for a full minute before they consider releasing at a target but this is dangerous and it throws off your rhythm. You only need to go around once and then you're ready for the final swing and release.
Note below how my hand is always a little ahead of the pocket. It's required by the law... of physics. You can't push string.